Float switch
From HacDC Wiki
This is the source code for the float switch 3d printed parts for the water level detector for the Cheap Chinese Laser. It is made in two parts: the head and the base. You also need 4 pieces of 1/4-20 all thread to connect the two of them and 8 nuts. The base is internally threaded. The head needs nuts top and bottom. Washers would be good too.
/* low water level detector safety interlock for cheap Chinese laser at Hac DC This water level detector is a two piece assembly connected by threaded rod. This model uses 1/4-20 rod. The lower foot has a 40mm home in the bottom to insert a pingpong ball as the float. James Sullivan 4-30-17 Mk 2 - calculated threads OpenSCAD version 2015.03-1 */ ppbd=40; //ping pong ball diameter ppbw=2.7; //ping pong ball weight in grams shd=2; //switch hole diameter shp=10; //switch hole pitch, i.e. center to center spacing of mounting holes on microswitch wlh=200; //water level height sbw=6; //switch body width nfw=4; //nut face width, switch mounting nuts nt=1; //nut thickness, switch mounting nuts thick=5; //thickness fph=thick*3;//foot pillar height eps=0.1; //epsilon tol=0.5; //tolerance br=50; //base radius rod=25.4/4; //rod outer diameter tpi=20; //threads per inch bfw=ppbd+2*thick; //base flange width $fn=40; function mod(num,den) = num - floor(num/den)*den; //dimensions taken from Front Door Switch Holder wr=4; //wrench size for nuts width across flats nh=1; //nut height, depth of nut sockets $fn=40; //head module head() { difference(){ union(){ for(angle=[45:90:315]){ rotate([0,0,angle]) translate([ppbd/2+rod/2+tol,0,0]) cylinder(d=rod+thick*2,h=thick); //leg cylinders } cylinder(h=thick,r=ppbd/2+rod/2+tol-thick/2); } translate([0,0,-thick/2]) cylinder(h=thick*2,r=ppbd/2+rod/2+tol-3*thick/2); for(angle=[45:90:315]){ rotate([0,0,angle]) translate([ppbd/2+rod/2+tol,0,-thick/2]) cylinder(d=rod,h=fph); //leg holes } } translate([sbw/2,(ppbd+rod+tol-2*thick)/(-2),0]) cube([thick,ppbd+rod+tol-2*thick,thick]); translate([sbw/2,shp/2,thick]) difference(){ //switch mounting block, aligned with z-plane and x-plane, centered on y-plane translate([0,-shp/2-nfw,0]) color("green") cube([thick,shp+2*nfw,2*nfw]); for (y=[-shp/2,shp/2]) { translate([thick/2,y,nfw]) rotate([0,90,0]) cylinder(d=shd,h=thick*2,center=true); //screw holes translate([sbw-nh,y,nfw]) union(){ //nut sockets for (ang=[0,120,240]) rotate([ang,0,0]) cube([nh*2,wr,wr/sqrt(3)],center=true); } } translate([sbw/2+thick,bfw/2-nfw-shp,nfw]) union(){ //center nut socket cube([nh*2,wr,wr/sqrt(3)],center=true); rotate([120,0,0]) cube([nh*2,wr,wr/sqrt(3)],center=true); rotate([240,0,0]) cube([nh*2,wr,wr/sqrt(3)],center=true); } } } module socket(nd,tpi,tl,thick) { ror=nd/2; //rod outer radius pitch=25.4/tpi; //thread pitch in mm td=pitch*3/4; //thread depth in mm rir=ror-td; //rod inner radius sor=ror+thick; //socket outer radius vert= [for (ang=[0:360/$fn:720]) ang<=45 ? [cos(ang),sin(ang)]*rir : ang<180 ? [cos(ang),sin(ang)]*(rir+td*(ang-45)/135) : ang<=225 ? [cos(ang),sin(ang)]*ror : ang<360 ?[cos(ang),sin(ang)]*(rir+td*(360-ang)/135) : [cos(ang),sin(ang)]*sor]; path1=[for(p=[0:$fn]) mod(p,$fn) ]; path2=[for(p=[0:$fn]) mod(p,$fn)+$fn ]; linear_extrude(height=tl,center=false,convexivity=20,twist=tl/25.4*tpi*360){ polygon(points=vert,paths=[path1,path2]); } } //foot module foot(){ difference(){ union(){ translate([0,0,thick/2]) cube([ppbd+2*thick,ppbd+2*thick,thick],center=true); for (angle=[45:90:315]){ rotate([0,0,angle]){ translate([ppbd/2+rod/2+tol,0,0]) socket(rod,tpi,fph,thick); //pillar translate([0,-thick,0]) cube([br-thick,thick*2,thick]); //leg translate([br-thick,0,0]) cylinder(r=thick,h=thick); //foot } //end rotate } //end for } //end union translate([0,0,-eps/2]) cylinder(d=ppbd+tol,h=fph+eps); //ping pong ball entry } //end difference } //end foot module head();